Epilepsy is among the most common serious neurological disorders. There are many shortcomings in the understanding of the epidemiology of epilepsy mostly because of methodological problems (diagnostic accuracy, case ascertainment and selection bias). No specific study has been devoted to drug-resistant partial epilepsy. Data such as frequency and severity of seizures, duration of the disease, or drug use are often lacking. The overall incidence of epilepsy is about 50 cases per 100,000 persons and the prevalence is about 5 per 1,000 persons in developed countries. It appears that 30 to 40 p. 100 of epileptic patients will not be completely free of seizure. Up to 70 p. 100 of them have a partial non idiopathic epilepsy. Based on literature review, about 10 p. 100 of epileptic patients could meet the criteria of drug-resistant epilepsy.